Film-type sectional evaporator



Feb. 8, 1927. 15175082 .L RIcE FILM TYPE SECTIONAL EVAPORATOB Filed MarchB. 1925 3 Sheets-Sheet 1 J INVENTQR BY ,0 I ma; WWW

ATTORNEY Feb. 8,1927;

J. PRICE FILM TYPE SECTIONAL EVAPORATOR Filed March 5, 1925, 3 Sheets-Sheet 2 INVENTOR M m 209;, ATFOR Y Feb. 8, 1927. J. PRICE FILM-TYPE SECTIONAL EVAPORATOR Filed March 5. 1925 3 Sheets-Sheet 3 lNVEIfITOR ATI'ORNEY aosnrirrmcn, or s'rArLnToN, NEW YORK, ASSIGNOR TO THE GRISCOM-RUSSELL com- @dtented Feb. 8 1927 barren ems mm tannin or BANY, OF YORK, 11'. Y-{A CORPORATION OF DELAWARE.

. FEM-TYPE sEo'rroNAL nvAPoR Aron."

. Application filed March 3, 1925. Serial No. 12,906.

The present invention relates to an evaporator of the so-called=' film type for furnishing purified boiler feed water and has to do particularly with the distribution of the liquid to be treated over the heat transferring surfaces of the evaporator. I In evaporators of the film type the m1- pure liquid is distributed over the heating surfabe in the form of a film'or layer and evaporation of the liquid is effected during the-time that itfis thus vspread out upon theheatin surface. Thismethod of evaporation is in contrast to that which occurs in. the erdinary type of evaporator wherein the heating tubes or coils are wholly or para tiallysubmerged in the body of liquid which is being'evaporated. In the film type evaporator steam or other heating fluid is passed through theheat transferring tubes and the of the tubes.

water is spread out as a film on the surface entire tube surface should at all times be covered with liquid so that the. entire heat transferring surface will beefiectlve in actively heating the liquid.

The heating element in film type evaporators commonly consists of a large number of tubes arranged in substantial par allelism. and supported at their respective ends to constitute 'a unitary tube bundle. -Heating elements of this nature consisting of a large number of closely grouped tubes are open to the objection that the tubes of the bundle are relatively inaccessible for .35 u Scale formin impurities precipitated from purposes of inspection cleamng or repair.

the liquid un er treatmentaccumulate rap-.

. tubes and soon impair the character of the idly on the surfaces of the heat trangferring heat transfer with the result that equent 'removal of .the scale is required. In .my copending application, Serial No. 644,971, filed June- 12, 1923, there is shown a film,-type evaporator of this general character employing'in its heating element tubes which are slightly bowed for the purpose of crack in temperature-thesebowed tubeswill ex mg 0 accumulated scale. Upon chan es and in this manner will "serve to loosen and crack off the scaly deposit of impurities which has been precipitated from the liquid For the best operation the shell to thereby afiord easy access to every tube in the heat transferring element.

It is a principal object'of the present invention to provide a film type eva orator of the class described having its eating element built in a pluralit of independently removable sections and having in articular provision for the uniform distrlbution of the incoming liquor over the entire surface of all of the tubes of the heat transferring clement, this distribution of the liquid being effected in such fashion as not to. interfere with the independent removal of the individual tube sections. This sys tem of liquid distribution is accomplished by providing for the admission of water lnto a principaldistributing element which in turn discharges into a plurality of indi-,

vidual distributing elements, each of which is designed to distribute the liquid upon the surface of the tubes of one section of the heat transferring element. The individual distributing elements are constructed as an integral partof the respective sections of the tube bundle so that each of the independently removable sections consists of its quota of heat transferring tubes with their appropriate nd supports and the distributing element pertaining to that section.

It is also an object of this invention to provide in an apparatus of the class referred to, inlet means capable of admitting to the principal. distributing element in an orderly fashion and without splashing large uant'ities of the liquid to be treated. Simiarly, provision is made for discharging liquid from the principal distributing ele- 'ment into'the respective individual distributing elements in such fashion as to direct the. liquid along the lengths of the individual elements'to thereby'insurethe presence of liquid throughout the extent of each distributing element and at the same time avoid splashing and waste of liquid. This arrangement is of particular advantagefor' marine work in that'a uniform distribution of the impure liquid over the heat transferring surfaces is effected even thou h the apparatus may be subject. to the uence of the pitch and roll of the ship.

f It is a-still further object to provide a film type evaporator which is particularly adapted to the employment of the bowed tube'construction for the purposes of, scale removal. In the present structure each of the respective individual distributing eleinstance, by successively passing steam and cold water through the tubes.

A preferred embodiment of the invention is illustrated in the accompanying drawings. In said drawings, Figure 1 is a vertical sectional View taken longitudinally through an evaporator embodying the invention, Figure 2 is an end view partly in section taken from the'front of the apparatus of Figure 1, Figure 3 is a transverse sectional view taken on line 33 of Figure 1, Figure 4 is a partial sectional view taken on line H of Figure 1, and Figures 5 and 6 are detail views illustratingthe mounting of the individual sections of the heating element.

Referring to the drawings, 1 indicates the shell of the evaporator wherein evaporation of the impure liquid take place. The heat transferring element consisting of a plurality of tubes supported at their respective ends and extending in substantial parallelism throughout the major portion of the length of the evaporator shell is indicated at 2. Heating steam is admitted through the inlet opening 3 from whence it passes into compartment 4; which is in communication with the initial end of the tubes 2. It then enters the tubes 2 and, after traversing their length, emerges into the chamber 5 at the other end of the heating element. The heating steam is practically entirely condensed during its passage along the heatin tubes 2 and the condensate which ,is disc arged into the chamber 5 enters the return or drain tube 6 by means of which it passes back along the length of the shell'and is passed, out of the apparatus through the discharge opening 7. The heating tubes 2 are sup ported at their respective ends in stationary tube sheets 12. Each of the tubes is slanted slightly along its length so that the discharge ends of the tubes are lower than their respective inlet ends. \Vith this arrangement, satisfactory drainage of the condensate into the chamber 5 is insured. Each of. the tubes is slightly bowed so that wheii subjected vto an abrupt temperature change the resulting longitudinal expansion or contraction will alter the degree of bowing of the tube and will thus flex theheat transferring surfacesin such fashion as to crack, 011' scale deposits which have accumulated on it, after the fashion disclosed in my above noted pending application. I

The incoming impure liquid is admitted to the apparatus through the inlet opening 8 from whence it passes down upon the heating tubes 2. The liquid is spread out upon the tubes as a relativelythin film or layer and the heating medium within the tubes serves to effect vaporization of the liquid while thus distributed upon the tube surfaces. The excess of water which passes over the tubebundle .without being evapo- 9 provided at the bottom of the evaporator shell from whence it is commonly recirculated by pumping it into the apparatus again through the inlet opening 8. It is understood that suitable provision for discharging concentrated liquid from the system is made according tothe usual evaporator practice so that a substantially constant liquiddensity may be maintained in the apparatus. the heat transferring surfaces rise to the top of the apparatus and, after passing the separator bafile 10, are discharged through the outlet 11 following the course indicated by the arrows.

' The present invention contemplates a heating element comprising a plurality of independently removable sections. Eachof thesesections consists of one or more vertical rows of the heating tubes 2 together- The vapors generated at rated accumulates in a collection chamber 15 which secure that element in place and then sliding the element forward along its,

"track 14 to thus bring it to the exterior of the shell for the purpose of inspection or repair. The details of the mounting by means of which the individual elements --may be withdrawn from the apparatus are shown in Figures 5 and 6.

The impure liquid entering through the inlet opening 8 is directed into a masterdistributing tray or trough 16. The inlet 8 communicates directly with a cylindrical element 17 which extends down into the master distributing element 16 and is provided on opposite sides with slots or weir openings 18 for the purpose of discharging the ineomipg quantity of liquid into the element 16 In an orderly discharge stream directed along the length of .the element; By providingthese weir openings 18 itis possible to supply the master distributing element 16 with a large quantity of liquid and to distribute the liquic uniformly along the len th of the element and accomplish fhisrdvit out splashing or overflowing of'the ach of the vertically disposed sections mama 13 of'the-heating element includes a erforated distributing tray 19 positioned; at

the top of the section. and extending throu bout the length of the heating tubes 2. T16 tray 19 is rigidly secured to the tube sheets 12 atthe ends of the section and is therefore an integral partof the section and is removable with it. Each of the trays 19 receives a supply of the incoming liquid and serves to distribute that liquid as a spray over all of the tubes included in that section. By reason of the rigid connections between the tube sheets 12 and the distributing tray 19 the tray serves as a spacing element to maintain the tube sheets a fixed distance. apart. This function isof particular value where the bowed tubes are employed for the reason that tube sheets must be held rigidly spaced while the tubes are subjected to temperature change in'order spond in number to the individual distributing trays 19 and are positioned -respectively above the various trays. 19 after the fashion shown in Figure 4. The liquid admitted to the master tray 16 is thus dis charged in measured amounts through the various openings 20 into the respective trays 19. The orifices 20 serve to effect an orderly discharge of the liquid into the individual trays 19 and thus serve to distribute the liquid along the length of'thetray so that the entire length of the heat transferring tubes will receive a supply of the incoming liquid.

The present invention contemplates essentially a liquid distribution means in a film type evaporator wherein a substantially uniform distribution of the impure liquid over the entire heat transferrin secured under all conditions 0 operation. The master distributing tray effects a proportionment of the liquid to the-various sections of the heating element and the individual distributing trays distribute and spray upon the tubes of the respective sections that liquid which has been apportioned to each section. This apparatus is of par ticular advantage in marine work in that the effect of pitching and rolling of the ship on the distribution of the liquid is minimized. I

I claim: 1 A heat exchanger of the class described,

surface 7 iscomprising a plurality of slightly bowed.

heat transferring tubes arrangedin substantial parallelism, end supports for said tubes and a distributing element extending between said end supports for receiving liquid and distributing it upon said tubes, said distributing element .being rigidly secured to said end supports to thereby serve as a rigid spacing element for maintaining said end supports a fixed distance apart.

2. A heat exchanger of the class described,

having a heating element comprising a plurality'of slightl bowed tubes, tube sheets for supporting he respective ends of said tubes, means at the bottoms of said tube sheets for effecting a rigid s acing thereof and a distributing tray at t e top of the heating element for effecting distribution of liquid .upon the heat transferring tubes and serving to space said tube sheets a fixed I distance apart.

3. A heat exchanger of the class described, having a heating element comprising a plurality of independently removable sections,

eachof said sections having a plurality of slightly bowed tubes arranged in substantial parallelism, end supports for said tubes and a distributing element for effecting distribution-of liquid upon thetubes of that'section and serving also as a spacing member a for maintaining said tube supports a fixed distance apart.

4. In a heat exchanger of the class de-- scribed, a tube bundle comprising a plurality of independent sections, a tray positioned above each of said sections for supplying liquid thereto, a master tray for receiving incoming liquid and having a plurality of orifices for directing said liquid into said respective distributui trays along the length thereof and i et means comprising a horizontally discharging orifice for passing ,the incoming liquid into said master tray lengthwise thereof.

5. A heat exchanger of the class described, H

comprising a heating element consisting of a plurality of independent sections, a master tray extending transversely of said heating element, inlet vmeans for introducing liquid into the apparatus, a distributing member having a horizontally discharging orifice. 'for' directing liquid in an orderly fashion along the'len h of said master tray to avoid splashing o the liquid, and individual perforated distributing trays positioned above each of said sections for distributing liquid thereupon, said master tray having horizontally discharging orifices for directing liquid in orderly fashion into said receiving-trays along the length thereof.

In testimony whereof I aflix my signature.

JOSEPH PRICE. 

